Two numbers have a difference of 0.7 and a sum of 1. what are the numbers?

In order to determine the value of the numbers, we can set up algebraic equations to solve. For this case, we need to set up two equations since we have two unknown numbers. We do as follows:
 let x = first number and y = second number
 From the problem statement, we set up equations.
 Equation 1 - the numbers have a difference of 0.7
 x - y = 0.7
 Equation 2 - the numbers have a sum of 1
 x + y = 1
 Solving for x and y via substitution method,
 x - y = 0.7
(1-y) - y = 0.7
1 - 2y = 0.7
-2y = 0.7 - 1 = -0.3
y = 0.15 or 3/20
 x - 0.15 = 0.7
x = 0.85 or 17/20
 Thus, the two numbers are 0.15 and 0.85.