30+5=5+30 with commutative property or 30+5=35
Answer: The mechanic worked 3hrs 95 minutes
Step-by-step explanation:
Answer:
Step-by-step explanation:
we know that
The simple interest formula is equal to
where
A is the Final Investment Value
P is the Principal amount of money to be invested
r is the rate of interest
t is Number of Time Periods
in this problem we have
The inequality that represented this situation is
substitute the values and solve for t
![t \leq [(7,020/4,500)-1]/0.03](https://tex.z-dn.net/?f=t%20%5Cleq%20%5B%287%2C020%2F4%2C500%29-1%5D%2F0.03)
x = quarts of 30% acid solution
y = quarts of 65% solution
x + y = 175
Each quart of the 30% solution contributes 0.30x quarts of acid; similarly, each quart of the 65% solution contributes 0.65y quarts of acid. So
0.3x + 0.65y = 0.55*175 = 96.25
That is, the chemist wants 175 quarts of a new mixture with a 55% concentration of acid, which comes out to 95.25 total quarts of acid. The total amounts of acid from either sides of this equation must balance out.
Now solve for x and y:
x + y = 175 ==> y = 175 - x
0.3x + 0.65y = 96.25 ==> 0.3x + 0.65(175 - x) = 96.25
==> 0.3x + 113.75 - 0.65x = 96.25
==> 17.5 = 0.35x
==> x = 50 ==> y = 125
