Answer:
12/28
Step-by-step explanation:
3 x 4 = 12
7 x 4 = 28
Substitution is where we first Isolate one of the unknowns, express it in terms of the other unknown, and replace the isolated unknown with the other unknown in another equation. So that each time we only need to deal with one unknown. I think you'll get a better idea here:
First name these 2 equations with 1 and 2.
4x + 5y = 7 (1)
y = 3x + 9 (2)
Since y is already isolated in (2), so we can skip the isolation step and continue to substitute.
Substitute (2) into (1).
4x + 5(3x+9) = 7
Expand.
4x + 15x + 45 = 7
Group.
19x + 45 = 7
Shift +45 to the other side and turn it into -45.
19x = 7 - 45
19x = -38
Shift x19 to the other side, turn it into /19.
X = - 38/19
X = - 2
Now we solved x already, we can just substitute x= - 2 back to equation (2).
y = 3(-2) + 9
y = - 6 + 9
y = 3
So, the answers are
x = - 2
y = 3
So that would be the same thing as 5 4/5 - 3 2/7
Put them in mixed fractions to become 29/5 - 23/7
Multiply one side by 7 and one side by 5 to get the same denominator
203/35 - 115/35
Now subtract the numerators to get
88/35
Or if they want it inixed numbers then 2 18/35
