Subtract 39 from both sides
-7x = -4 - 39
Simplify -4 - 39 to -43
-7x = -43
Divide both sides by -7
x = -43/-7
Two negative make a positive
<u>x = 43/7</u>
<em>For the second equation;</em>
Simplify brackets
7x + 7 = 4
Subtract 7 from both sides
7x = 4 - 7
Simplify 4 - 7 to -3
7x = -3
Divide both sides by 7
<u>x = -3/7</u>
Answer:
The amount of water must be added to this task = 60 
Step-by-step explanation:
Let amount of water added = x
Then from the given conditions
A chemist would like to dilute a 90-cc solution that is 5% acid to one that is 3% acid. So
90 (0.05) = 0.03 ( 90 + x )
4.5 = 2.7 + 0.03 x
0.03 x = 1.8
x = 60
Therefore the amount of water must be added to this task = 60
10 cheese pizzas
use simple ratio, 3:2 (3 pepperoni for every 2 cheese)
to make the ratio bigger, we substitute the "3" pepperoni for "15" pepperoni. then take the new amount, 15/3 original, you get 5. then multiply the 2 original cheese pizzas by that 5, and you get 10 cheese pizza's.
hope that helps
9 * 20 = 180
24 has 4 more than that, so multiply 9 to 4 and add it to 180.
9 * 4 = 36
180 + 36 = 216
So 9 * 24 = 216
