Four times a number plus three times a second number is -9. Twice the first number plus the second number is three. Find the numbers.

Question

asked Mar 3, 2020 207k views

2 Answers

Matti Lehtinen · Answer 1 · 2020-03-09T15:29:01+0000

The first number is: 9

and the second number is: -15

Let the first number be : a

and the second number be: b

Now, we have:

Four times a number plus three times a second number is -9.

i.e. we have : 4a+3b= -9--------(1)

Also,

Twice the first number plus the second number is three.

i.e. 2a+b=3

i.e. we have: b=3-2a------(2)

Now, putting the value of b in equation (1) we have:

$4a+3(3-2a)=-9\\\\4a+3* 3-3* 2a=-9\\\\4a+9-6a=-9\\\\4a-6a=-9-9\\\\-2a=-18\\\\2a=18\\\\a=(18)/(2)\\\\a=9$

and on putting the value of a in equation (2) we have:

$b=3-2* 9\\\\b=3-18\\\\b=-15$