[a] x = 175 - 7.5p
For a, we are isolating the x variable to one side of the equation.
0.4x + 3p = 70
0.4x = - 3p + 70
x = - 7.5p + 175
[b] x = 115
For b, we are solving for x when p = 8.
x = - 7.5p + 175
x = - 7.5(8) + 175
x = 115
So
lets say we have
a/b=2a/2b
we know that if we invert one and multiply it by the other (divide them), we get 1 because a/a=1 where a=a
so
2/3 and 4/6 are equivelent because if you divide them we get 12/12=1
2/3 and 8/12 are equivilent because if you divide them we get 24/24=1
and sinde 2/3=4/6 and 2/3=8/12, 2/3=4/6=8/12
they are equivlent
