From 6 to 18, 6 was multiplied by 3. To keep the equality, we must multiply the other side by three as well. Therefore, x is equal to 2*3 which equals 6.
x=6.
5:7
(x+3):7
For this one, the second value did not change, so we know that x+3 has to equal 5. Therefore, x=2.
