Display all the users with grade and subject equals to a Teachers subject and grade he teaches

Hi guys... I want to display all the users with roles = learners, grade equals to specific Grade and subjects equals to a specific subject... I have hardcoded it and works OK but How do I do it dynamically?

ClassController

public function index()
    {
        return view('classes.index');
    }

index.blade.php

@if(count(Auth::user()->grades) > 0)
        @foreach(Auth::user()->grades as $grade)
        <div class="col-md-2">
            <div class="card shadow mb-4">
                <div class="card-body">
                    <form method="POST" action="{{ route('class.show') }}">
                        @csrf
                        <h5 class="font-weight-bold">{{$grade->name}}</h5>
                        <input type="hidden" name="grade" value="{{$grade->name}}"/>
                        <hr>
                        <h6 class="font-weight-bold">Subjects:</h6>
                        <ul>
                            @foreach(Auth::user()->subjects as $subject)
                                <li>{{ $subject->name }}</li>
                                <input type="hidden" name="subjects[]" value="{{$subject->name}}"/>
                            @endforeach
                        </ul>
                        <hr>
                        <div class="row">
                            <div class="col-md-12">
                                <button type="submit" class="btn btn-primary"><i class="fas fa-graduation-cap fa-fw mr-2"></i>View Learners</button>
                            </div>
                        </div>
                    </form>
                </div>
            </div>
        </div>
        @endforeach
    @else
        <h3 class="col-md-12 offset-md-5">No Grades to display</h3>   
    @endif

Here is where I have hard coded the values (Grade 12, Mathematics) and it works, but I want to do it dynamically... ClassController

public function show(Request $request)
    { 
       $learners = User::whereHas('roles', function($query){
             $query->where('name', 'learner');
        })->whereHas('grades', function($query){
            $query->where('name', 'Grade 12');
        })->whereHas('subjects', function($query){
            $query->where('name', 'Mathematics');
        })->get();
        }
        return view('classes.show', compact('learners'));  
    }