At a cafe
2 teas + 1 coffee cost= £3.40
1 tea and 4 coffees cost=£7.30
work out the cost of 1 tea and the cost of 1 coffee?

step by step explanation,

simultaneous equations

price of 1 tea = t

price of 1 coffee = c

2t + 1c = 3.40

1t + 4c = 7.30

multiply second equation by 2 and rewrite

2t + 1c = 3.40

2t + 8t = 14.60

subtract equations

0 - 7t = -11.20

- 7t = -11.20

7t = 11.20

divide by 7

t = £1.60

the price of 1 tea is £1.60

sub t = 1.60 into 2t + 1c = 3.40

2 (1.60) + 1c = 3.40

3.20 + c = 3.40

subtract 3.20 on both sides

c = £0.20 (or 20p)

the cost of one coffee is 20p

= 5

step-by-step explanation:

to find the 15th term substitute n = 15 into the nth term formula

= (- 3 × 15 ) + 50 = - 45 + 50 = 5