Can someone explain to me how to do this i worked it out but i'm stuck

We have an expression and we know what the variables are equal.
We can just replace all variables with their values.

Now the expression becomes .
Just use the order of operations to solve.

First, solve all exponents.
There is one exponent. Simplify.

= 4(4) - 2(7) ÷ 7 + 2(2)

Now solve all multiplication and division from left to right.

4(4) - 2(7) ÷ 7 + 2(2) =
16 - 2(7) ÷ 7 + 2(2) =
16 - 14 ÷ 7 + 2(2) =
16 - 2 + 2(2) =
16 - 2 + 4

Now do the same for addition and subtraction.

16 - 2 + 4 =
14 + 4 =
18

So, the answer is 18.