It’s B. When dividing by -2, he did not change the direction of the sign
Answer:
The number is 8
Step-by-step explanation:
<em>2x +5 =21 </em>
2x= 21-5
2x=16
2x/2=16/2
x=8
To check
8×2=16
16+5=21
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]
Answer:
first one:
Area of a circle = π*r²
diameter (they gave) = 30ft
radius = diameter/2 = 15ft
π*15²= 706.85834705770347865409476123789
to nearest tenth= 706.9 ft
second question:
circumference = 2*π*r or d(diameter)*π
diameter = 30ft
30*π = circumference = 94.247779607693797153879301498385
in terms of π = 30π
