If 4m-7n=10 and 2m+2n =4 what is the value of 2m-9n?

Question

amistre64 · Answer

they want you to find the common solution tothe first 2 equations and use those numbers in the last one

a_clan · Answer

or simply subtract second from  first

amistre64 · Answer

id multiply 2nd by -2 then add them together

anonymous · Answer

I dont really understand how to do that though... I've tried a lot of numbers for finding the solution to the first one, but it never worked out for the second one, or vice versa

amistre64 · Answer

trial and error is a shot in the dark; you have to use numerical methods such as substitution or elimination

a_clan · Answer

subtract second equation from first equation

amistre64 · Answer

4m-7n=10
2m+2n =4  <-- multiply this one by -2


  4m-7n=10
-4m-4n =-8  ; now add them together
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  0 -11n = 2 , now solve for n

anonymous · Answer

oh... thank you

amistre64 · Answer

once you know "n"; solving for m is easy :)