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WITCHER [35]
3 years ago
13

The difference of two numbers, a and b, is 21. The difference of 5 times a and two times b is 18. What are the values of a and b

? A. 4,1 B. -19,40 B. 20,1 C. 30,9 D. -8,-29
Mathematics
1 answer:
PSYCHO15rus [73]3 years ago
6 0
A-b=21
5a-2b=18

We can use substitution here. Take the first equation and solve for A. (Picking this one because it's easy)

a = 21+b

Plugin to the second equation:5(21+b)-2b=18
Simplify: 105 + 5b - 2b = 18
Simplify: 105 + 3b = 18
Subtract both sides: 3b = 18-105
Simplify: 3b = -87
Divide: b = -29

Plug back into the first: a=21+b
a = 21 - 29
a = -8

Option D

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