Answer:
$3213
Explanation:
You want to know the total spent on rent and food if rent is 7/20 of your budget and food is 1/2 of your budget of $3780 per month.
Amounts
The amount spent on each item is the product of the fraction of the budget it is and the total amount being budgeted (your income).
rent = 7/20 × 3780 = 1323
food = 1/2 × 3780 = 1890
The total spent on these items is the sum of these amounts:
rent + food = 1323 +1890 = 3213
A total of $3213 is budgeted for rent and food.
__
Additional comment
Your calculator can figure this handily.
You can factor out the income amount and add the fractions first:
(7/20·3780) +(1/2·3780) = 3780(7/20 +1/2) = 3780(7/20 +10/20)
= 3780(17/20) = 3213