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
−
4
x
+
7
=
2
Step 1: Subtract 7 from both sides.
−
4
x
+
7
−
7
=
2
−
7
−
4
x
=
−
5
Step 2: Divide both sides by -4.
−
4
x
−
4
=
−
5
−
4
x
=
5
4
All you have to do is write your question and someone will answer. For example, instead of writing "I do not understand how I find answers on here" you would ask something like what is 9*5? Then 2 people will see your question and answer. There are no pre-recorded answers, everything happens live. Hope this helps!
<span>At a 3% increase you would use 1.03 * 1000 L = 1030 L next year</span>
