A few days ago
The sum of a certain num. and a second num. is 21.The second num. minus the first num. is -57.Find the num..?
Help please..thank you=)
Top 3 Answers
A few days ago
Favorite Answer
first number = x
second number = y
x + y = 21
y – x = -57 –> multiply this whole thing by -1–> x – y = 57
–> x = y + 57
substitute
(y + 57) + y = 21
2y + 57 = 21
2y = -36
y = -18
plug value of y back in original equation
x + (-18) = 21
x = 39
x = 39, y = -18
0
A few days ago
x = the first number
y = the second
x + y = 21
y – x = -57
solve for y
y – x + x = -57 + x
y = -57 + x
substitute y
x + (-57 + x) = 21
simplify
2x – 57 = 21
2x = 78
x = 39
substitute x
y – x = -57
y – 39 = -57
y = -18
x = 39
y = -18
0
A few days ago
A + B = 21
B – A = -57
—
B + 57 = A
57 + 2B = 21
2B = -36
B = -18
A = 21 – B
A = 39
0
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