Answer:
£21
Step-by-step explanation:
Cost of 18 drinks = £54
Cost of 1 drink
= Cost of 18 drinks/18
= £54/18
= £3
Cost of 7 drinks
= Cost of 1 drink × 7
= £3 × 7
= £21
91. The square has an area of 49, and the triangle has an area of 42. Added together, you get 91.
Step-by-step explanation:
a.
Let's give the starting amount of water as s. Every minute, 2 inches of water are lost, meaning that given the starting amount, s, we subtract 2 inches from s every minute, so s - 2 every minute = height of water left, so s - 2t (t representing minutes) = h
To figure out s, we simply plug our known value -- 9 minutes in and 11 inches left. s - 2(9) = 11, s-18=11, s= 29
29 - 2t = h
b. We know that we cannot have negative minutes, so the minimum amount of time that makes sense is 0. To figure out the maximum, we stop counting how much time has occurred when there is no water left, so we have to figure out when h = 0
29-2t = h = 0
t=14.5
Therefore, anything between 0 and 14.5 minutes makes sense
c. Anything between 0 and 29 makes sense because the height of water cannot be negative and we cannot get higher than the starting amount
