Find the value of two numbers, when their sum is 21 and their difference is 7.
x = one number
y = other number x + y = 21 {their sum is 21} x  y = 7 {their difference is 7}  2x = 28 {added the two equations} x = 14 {divided each side by 2} x + y = 21 {first equation} 14 + y = 21 {substituted 14, in for x, into first equation} y = 7 {subtracted 14 from each side} the two numbers are 14 and 7 Ask the House
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