Question

Solve:

4a+2c=70
8a+12c=196
Use the elimination method or substitution method to solve
Enjoy :)

Answer 1

4a + 2c = 70            ; a = 14 ; c = 7 ; 4(14) + 2(7) = 70 ; 56 + 14 = 70 ; 70 = 70
8a + 12c = 196        ; 8(14) + 12 (7) = 196 ; 112 + 84 = 196 ; 196 = 196

Get the value of a:

4a + 2c = 70
4a = 70 - 2c
4a/4 = (70 - 2c) / 4
a = (70 - 2c) / 4

Substitute the value of a:

8a + 12 c = 196
8 ((70 - 2c)/4) + 12c = 196
(8*70)/4 - (8*2c)/4) + 12c = 196
(560 / 4) - (16c / 4) + 12c = 196
140 - 4c + 12c = 196
-4c + 12c = 196 - 140
8c = 56
8c / 8 = 56 / 8
c = 7

a = (70 - 2c) / 4
a = ((70 - 2(7))/4
a = (70 - 14)/4
a = 56 / 4
a = 14

Answer 2

♥ First lets find the value of a
Steps we can use:
$4a + 2c = 70$
$4a = 70 - 2c$
$\frac{4a}{4} = \frac{(70 - 2c)}{4}$
$a = \frac{(70 - 2c)}{4}$

♥Now we are going to substitute for the value of a...
$8a + 12 c = 196$
$8 ((70 - 2c)/4) + 12c = 196$
$(8*70)/4 - (8*2c)/4) + 12c = 196$
$(560 / 4) - (16c / 4) + 12c = 196$
$140 - 4c + 12c = 196$
$-4c + 12c = 196 - 140$
$8c = 56$
$8c / 8 = 56 / 8$
$c = 7$

Now moving onto A:

$(70 - 2c) / 4$
$a = ((70 - 2(7))/4$
$a = (70 - 14)/4$
$a = 56 / 4$
$a = 14$

Thus, if you follow these rules, you can solve:
c=7 a=14