Question

Solve each equation. Check your solution.

$-21=7-4y$

Short answer

The solution of given equation is $y=7$.

Step-by-step solution

Step 1. Given equation.

$-21=7-4y$

Step 2. Description of step.

Solve the given equation to find the value of y as,

$\begin{array}{c}-21=7-4y\\ \Rightarrow -21-7=-4y\\ \Rightarrow -28=-4y\\ \Rightarrow 4y=28\\ \Rightarrow y=\frac{28}{4}\\ \Rightarrow y=7\end{array}$

Step 3. Check solution.

In order to check the solution, put the value of yback in the given equation and see if it satisfies the equation, i.e. of left hand side is equals to right hand side, as:

$\begin{array}{c}-21=7-4y\\ \Rightarrow -21=7-4\left(7\right)\\ \Rightarrow -21=7-28\\ \Rightarrow -21=-21\\ \Rightarrow \text{true}\end{array}$

Hence, the solution $y=7$satisfies the equation.