Answer:
x = 136/35; y = -⁹/₁₀
Step-by-step explanation:
(1) 7x + 8y = 20
(2) 7x – 2y = 29 Subtract (2) from (1)
10y = -9 Divide each side by 10
(3) y = -⁹/₁₀ Substitute (3) into (1)
7x - 2(-⁹/₁₀) = 29
7x + 18/10 = 29 Subtract 18/10 from each side
7x = 29 - 18/10
7x = (290 - 18)/10
7x = 272/10 Divide each side by 7
x = 272/70
x = 136/35
x = 136/35; y = -⁹/₁₀
Check:
(1) 7(136/35) + 8(-⁹/₁₀) = 20
136/5 - 72/10 = 20
136/5 - 36/5 = 20
100/5 = 20
20 = 20
(2) 7(136/35) – 2(-⁹/₁₀) = 29
136/5 + 18/10 = 29
136/5 + ⁹/₅ = 29
145/5 = 29
29 = 29
Hi,
Here we are going to be working on isolating the variable y, and seeing what its value equates to.
To do this, we must try and get the variable y on one side of the equation by itself.
Let's look at step one -
<em>4y - 1 = 7
</em>
We want to get rid of the 1 since we need to isolate x. We do this by doing the inverse of its operation. Since 1 is negative, if we add positive 1 to it - we will get 0, thereby being closer to isolating y.
However, when we do something on one side of the equation we must do it on the other. This means we will add 1 on both sides.
<em>4y - 1 + 1 = 7 + 1
</em>
<em>4y = 8
</em>
<em />Remember how I mentioned we do the inverse of the operation? In this case, 4 is multiplying y. The inverse operation of multiplication is division. So, to get rid of the 4 - we must divide 4y by 4, on both sides.
<em>4y / 4 = 8 / 4
</em>
<em>y = 2
</em>
We now know the variable y is equal to 2.
Hopefully, this helps.
Adding more short sentences.
I believe the answer is 240.
8000 * .03 = 240
