Question

4 coffees and 12 lattes. Costs $61
12 coffees and 7 lattes. Costs $59.75
How much does a coffe and a latte cost

Answer 1

Answer:

Cost of a coffee is $2.5 and cost of a latte is $4.25.

Step-by-step explanation:

Let cost of 1 coffee be 'c' and cost of 1 latte be 'l' dollars.

Given:

4 coffees and 12 lattes cost $61.

12 coffees and 7 lattes cost $59.75.

∵ 1 coffee cost = $c$

∴ 4 coffees cost = $4c$ and 12 coffee cost = $12c$

∵ 1 latte cost = $l$

∴ 12 lattes cost = $12l$ and 7 lattes cost = $7l$

Now, as per question:

$4c+12l=61-----1\\12c+7l=59.75----2$

Now, multiplying equation (1) by -3 and adding the result to equation (2). This gives,

$-3(4c+12l)=-3(61)\\\\-12c-36l=-183\\12c+7l=59.75\\+\\----------\\0-29l=-123.25\\\\l=\frac{-123.25}{-29}=\ 4.25$

Now, plug in the value of 'l' in equation 1 to solve for 'c'. This gives,

$4c+12(4.25)=61\\\\4c+51=61\\\\4c=61-51\\\\4c=10\\\\c=\frac{10}{4}=\ 2.5$

Therefore, cost of a coffee is $2.5 and cost of a latte is $4.25.