solve a and b a3b 12 3a5b 2Solutiona 3b 12 1 3a 5b 2 2 L

solve a and b: a+3b= 12 3a-5b= -2

a + 3b = 12 ..........(1)

3a - 5b = -2 ...........(2)

Let us use the subsitution method:

from (1):

a = 12 - 3b

Now substitute a in (2):

3a - 5b = -2

3(12-3b) - 5b = -2

36 - 9b - 5b = -2

==> -14b = -38

==> b = 38/14 = 19/7

==> b= 19/7

Now we know that:

a = 12 - 3b = 12 - 3(19/7)

= (84 - 57)/7 = 27/7

==> a= 27/7