         NSLayoutConstraint.width(
             view:buttonBack,
             constant:kBackWidth)
+        
+        NSLayoutConstraint.height(
+            view:collectionView,
+            constant:kCellSize)
+        NSLayoutConstraint.bottomToBottom(
+            view:collectionView,
+            toView:self)
+        NSLayoutConstraint.equalsHorizontal(
+            view:collectionView,
+            toView:self)
     }
     
     required init?(coder:NSCoder)

            action:#selector(actionBack(sender:)),
            for:UIControlEvents.touchUpInside)
        
        addSubview(border)
        addSubview(buttonBack)
        
        NSLayoutConstraint.bottomToBottom(

import UIKit

class VLinearEquationsSolutionBar:UIView, UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout
{
    private let model:MLinearEquationsSolutionBar
    private weak var controller:CLinearEquationsSolution!
    private weak var collectionView:VCollection!
    private let kBorderHeight:CGFloat = 1
    private let kBackTop:CGFloat = 20
    private let kBackWidth:CGFloat = 60
    private let kBackHeight:CGFloat = 44
    private let kCellSize:CGFloat = 60
    
    init(controller:CLinearEquationsSolution)
    {
