Answer:
£110
Step-by-step explanation:
We know how much time it takes for a boiler and a radiator, and we need to know how much it will cost for 1 boiler and 4 radiators. We have an initial cost of £30, and since hes doing a boiler - which we know takes an hour - we can already add £20 for a start of £50.
Now, there are 4 radiators, that take 45 minutes each. We need to use this equation:

We divide by 60 because there are 60 minutes in an hour, and he charges by hour. So:

Now, to find out how much to charge, we need to figure out how much to add to the £50. Since it's £20 an hour, and it takes 3 hours to do the 4 radiators, we need to multiply:

Now we add our totals for a grand total of...

A. X+Y=50 y=x+20
B. 50-x=x+20 x=15 minutes
C. No, We know however much time Ted spends on the butterfly he spends 20 mins more on breast stroke. If he spends 45 mins on butterfly then he must spend 45+20= 65 mins on breast stroke. BUT we already know that he only spends 50 mins total, so it’s not possible
The answer to this question is 10.6
The answer for this is A.