First we need to find the value of a. To do this, divide both sides of the equation (2a = 10) by 2 to isolate the variable. 2a/2 = a, and 10/2 = 5. You are left with a = 5. Now we need to plug in the value of a in the second expression. 2(5) + 3. Two times five equals 10, plus three is 13. So, 2a + 3 = 13 when 2a = 10
