Question

15. The total monthly income, $D, of a salesman who
sells tyres consists of a basic salary of $600 and
a variable amount which depends on the
number of tyres he sells. For each tyre he sells,
he receives $8.
(i) If the salesman sells 95 tyres in a particular
month, find his total income for that month.
(ii) If the salesman's monthly income for a particular
month is $1680, calculate the number of
tyres he sells in that month.
(iii) Write down a formula connecting D and n,
where n is the number of tyres the salesman
sells in a month.
(iv) Draw the graph of D against n. Is D directly
proportional to n? Use your graph to explain
your answer.​

Answer 1

Answer:

(i) D=8n+600      

(i) Because, D is the total monthly income which is equal to $600 and(+) the amount of number of tyres he sell.(He receives $8 per tyre so,n multiply by 8 which is 8n)

As, D=8n+600    So, D=8(95)+600      D=1360

So, the income is $1360

(ii) As, D=8n+600        1680=8n+600         8n=1680-600        n=1080/8

n=135

So, the number of tyres is 135

(iii)  D=8n+600      

Because, D is the total monthly income which is equal to $600 and(+) the amount of number of tyres he sell.(He receives $8 per tyre so,n multiply by 8 which is 8n)

(iv)   answer is below.....