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Mr. GLENN, Math/Stat Expert
Category: Pre-Calculus
Satisfied Customers: 801
Experience:  math professor for at least 15 yrs
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I have a problem i cant figure out. The sum of two numbers

Customer Question

i have a problem i cant figure out. The sum of two numbers is 15. Three times one of the numbers is 11 less than five times the other. Find the numbers.
JA: The Math Tutor can help you get an A on your homework or ace your next test. Tell me more about what you need help with so we can help you best.
Customer: i figure it would be something like a + b = 15
JA: Is there anything else important you think the Math Tutor should know?
Customer: 3a = 5b - 11
Submitted: 1 month ago.
Category: Pre-Calculus
Expert:  Mr. GLENN replied 1 month ago.


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Expert:  Mr. GLENN replied 1 month ago.

Do you still need help on this?

Expert:  Mr. GLENN replied 1 month ago.

a + b = 15 -> equation 1
5a - 3b = 11 -> equation 2
multiply equation one by 3 both sides, you will get 3(a + b) = 3(15)
--> 3a + 3b = 45
then add this to equation two:
3a + 3b = 45
+ 5a - 3b =11
8a = 56

divide both sides by 8:
8a = 56
8a/8 = 56/8
a = 7
back substitute a = 7 in the original equation one:
a + b = 15 if a = 7, then
7 + b = 15
b = 15 - 7
b = 8

answers: a = 7, b = 8

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