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Four times a number minus twice another number is -8. The sum of the two number is 19.Find the numbers

User Aru
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1 Answer

5 votes
1. To solve this exercise, you must make a system of equations.

2. You have that four times a number minus twice another number is -8:

4x-2y=-8

3. And the sum of the two number is 19:

x+y=19

4. As you can see, you have two equations:

4x-2y=-8 (i)
x+y=19 (ii)

5. Let's clear the "x" from the equation (ii):

x=19-y

6. Now, you need to susbtitute x=19-y into the equation (i):

4x-2y=-8
4(19-y)-2y=-8
76-4y-2y=-8
76-6y=-8
-6y=-8-76
-6y=-84
y=-84/-6
y=14

7. You must susbstitute y=14 into the equation (ii) and clear "x":

x+y=19
x+14=19
x=19-14
x=5

The answer is: 5 and 14
User Fonewiz
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