Question

Question No : 20
M + N = 91
M-N = 21, then M = ?
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Answer 1

Step-by-step explanation:

Now,

M+N=91 let us take it as equation number one

M-N=21 is second equation

By equating equation 1 and 2

M+N=91

M-N=21

N gets cancelled.

so M=91-21

M = 71

Answer 2

from equation 1:

M = 91-N

Putting value of M in equation 2:

91-N-N = 21

91-2N = 21

-2N = -70

2N = 70

N = 35

Putting value of N in equation 1:

M+35 = 91

M = 91-35

M = 56

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