Since Igor had to re-do his medical training it is expected that his salary won't match his age or, in other words, he will not have the same salary as other surgeons his age. So, it is highly likely that Igor's point is the one showing age 42 and sallary 30000 £.
As for the last question, conclusions made from any graph are more reliable if there is more data. That means that including more surgeons in the research will give us even stronger relation between age and the sallary.
The answer is $18. Put the 38 in the place of b, b being the amount of times someone rides the bus. Hence, C=0.25(38) + 8.50. Then, multiply the multiplable numbers. You get 9.5. Add 9.5 and 8.50 to get 18.
