Part A
x = number of kilowatt-hours used
4x = represents the company charging Php 4 per kilowatt-hour
4x+8 = add on the base rate of Php 8. This represents the monthly cost
Answer: 4x+8
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Part B
We simply stick a "y=" in front to turn the expression into an equation. Specifically, this is a linear equation in slope-intercept form.
slope = 4, y intercept = 8
Answer: y = 4x+8
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Part C
Plug in x = 0 to compute y
y = 4x+8
y = 4*0+8
y = 0+8
y = 8
Answer: Php 8
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Part D
Instead of replacing x, we'll replace y with a number this time.
We'll use y = 1000 since this is the given bill. We want to find how much electricity used (in kwh) that will lead to this bill.
y = 4x+8
1000 = 4x+8
4x+8 = 1000
4x = 1000-8
4x = 992
x = 992/4
x = 248
Answer: 248 kwh
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Part E
This is very similar to part C. Instead of x = 0, we'll use x = 150
y = 4x+8
y = 4*150+8
y = 600+8
y = 608
Answer: Php 608
