Mr Watkins needs to buy some oil for his central heating, Mr Watkins can put up to 1200 litres of oil in his oil tank. There is
already 650 litres of oil in the tank. Mr Watkins is going to fill the
tank with oil. The price of oil is 70p per litre. Mr Watkins gets 5%
off the price of the oil. How much does Mr Watkins pay for the oil
he needs to buy?​

Step-by-step explanation:

1500 - 850 litres  = 650 litres

Cost = 650litres * 67.2p/litre *0.95   = 41496p = £41.50 to the nearest p (assuming the p represents pence Sterling)

The 0.95 is because he pays 95% of the basic price (i.e. 5% off)

problem:

f(x) = - 2/3x + 5; f(5/2)

substitute 5/2 in for x:

f(5/2) = -2/3(5/2) + 5

simplify the right side:

f(5/2) = -5/3 + 5

f(5/2) = 10/3

f(5/2) = 10/3

i hope this !