Question

40×(42-X)+12=1372 X=?

Answer 1

$40 \times (42 - x) + 12 = 1372 \\ 40 \times (42 - x) = 1372 - 12 \\ 40 \times (42 - x) = 1360 \\ 42 - x = 1360 \div40 \\ 42 - x = 34 \\ x = 42 - 34 \\ x = 8$