You have two unknown rates, so we need to develop two equations to solve for these unknowns (based on the information given on the problem statement):
5x + 10y = 725
x + y = 100
By substitution, we get:
5x + 10(100 - x) = 725
5x + 1000 - 10x = 725
-5x = 725 - 1000
-5x = -275
x = -275/-5 = 55
100 - 55 = 45
Thus:
The mechanic who worked for 5 hours charged his time at $55/hr, and the mechanic who worked for 10 hours charged his time at $45/hr.
To verify, plug and chug the results back into the original equations:
5(55) + 10(45) = 725
275 + 450 = 725
725 = 725 [OK]
55 + 45 = 100 [OK]
The percent of decrease would be 60%
Answer: D. 0.9967
Step-by-step explanation: To solve this, you need to do the z-score formula with both numbers. So 30-22/2.5 = 3.2. On the z-score chart, that equals .9993. Hold onto that number. Then you do the same with 15. 15-22/2.5 = -2.8. On the z score chart, that equals .0026. Subtract those numbers. .9993 - .0026 = .9967. It's not as compacted as it looks <3
The greatest commons factors are for 12 is 1,2,3,4,6,12 because 2 × 6 = 12, or 4 × 3 = 12, or 1 × 12 = 12 hope that help!
