X - 2y = - 9
7x + 2y = 1
x - 2y = - 9
(+)
7x + 2y = 1
___________
8x = - 8
x = - 1
- 1 - 2y = - 9
2y = 8
y = 4
i am a mathematics teacher. if anything to ask please pm me
Answer: y=175
Step-by-step explanation: y&x
y=kx
(Where k is a constant)
When y=60,x=12...we have
60=12k
Divide both side by 12
12k/12=60/12
k=5
Equation becomes y=5k
Finding y when x=35
y=5(35)
y=175
Using linear function concepts, it is found that:
- a) It costs $0.1 for each kilowatt hour of electricity used in excess of 250 kWh.
- b) f(90) = 46.6, which is the cost of 340 kWh of consumption in a month.
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A <em>linear function </em>has the format given by:

In which:
- m is the slope, which is the rate of change, that is, how much y changes when x changes by 1.
- b is the y-intercept, which is the value of y when x = 0.
The equation for the cost of h kilowatt hours (kWh) of electricity used in excess of 250 kWh is of:

Item a:
- The slope is of
, which means that it costs $0.1 for each kilowatt hour of electricity used in excess of 250 kWh.
Item b:

250 + 90 = 340.
f(90) = 46.6, which is the cost of 340 kWh of consumption in a month.
A similar problem is given at brainly.com/question/24808124
The inequality would be 50w + 100 >_ 18,000 ( the _ goes under the > but I cannot do that on my phone )