800 + 16x = 720 + 21x. Cancel out the 720 to get 80 + 16x = 21x. Subtract 16x from both sides to get 80 = 5x. Divide by 5 to get 16 = x, or x = 16. 16 hours. The charge is 800 + 16(16), = 720 + 21(16) which = 800 + 256 = 720 + 336 which = 1,056 = 1,056. Hope this helped!
One reason that negative numbers would not make sense for values of the variables is that the solution having a negative value is not valid. It might be that the expression represents a real word problem and a negative value will not make any sense. Hope this helps.
Answer:
105
Step-by-step explanation:
Area of a trapezoid is given by the formula:
A = (a+b)÷2×h
(where h is the vertical height, and a and b are the parallel lines)
Substituting values given gives us:
A = (6+15)÷2×10
A = 21÷2×10
A = 10.5×10
A = 105
Units will be m² as this is area.
Answer:

Step-by-step explanation:
1. 10xy · 4xy^3 = 
2. 10xy · -7xy = 
3. 10xy · 9y^2 =
Final step: add up all of those values together to make an equation!
Answer:

Final Answer: 
Answer:
Step-by-step explanation: