If you would like to solve the system of equations, you can do this using the following steps:
5p - 3r = 1 /*2
8p + 6r = 4
__________
10p - 6r = 2
<span>8p + 6r = 4
</span>__________
10p - 6r + 8p + 6r = 2 + 4
18p = 6
p = 6/18
p = 1/3
<span>5p - 3r = 1
</span>5 * 1/3 - 3r = 1
5/3 - 3r = 1
5/3 - 1 = 3r
5/3 - 3/3 = 3r
2/3 = 3r
r = 2/9
(p, r) = (1/3, 2/9)
The correct result would be <span>(1/3, 2/9)</span>.
When grading papers you can convert decimals into percents
-2 1/2 / 6 would be -5/12, just turn - 2 1/2 into a decimal and divide by 6 :)