Question

10+×=12 ×-18=22 ×:3=5 7×x=21

Answer 1

$10 + x = 12 \\ x = 12 - 10 \\ x = 2$

$x - 18 = 22 \\ x = 22 + 18 \\ x = 40$

$x \div 3 = 5 \\ x = 5 \times 3 \\ x = 15$

$7 \times x = 21 \\ x = 21 \div 7 \\ x = 3$