6 + 2x = 16
If we know that x =5, we can substitute 5 in for x. When we see a letter next to a number, that means we have to multiply the number in front of it by the value of the letter. In this case if x = 5, then we will have 6 + 2×5
2 x 5 = 10 and 10 + 6 = 16
