Hi,
your calculations are OK, but for me the following way is possible too:
First calculate the sum: (x+7)
The sum should be multiplicated by 3: (x+7)*3
Subtract 5 from this product: (x+7)*3 - 5
The result is 20:
3*(x+7) - 5 = 20 Expand the bracket:
3x + 21 - 5 = 20 Collect all constants at the RHS of the equation:
3x = 20 - 21 + 5 = 4 Divide both sides by 3:
x = 4/3
EB