Answer:
90 calories
Step-by-step explanation:
Calories : quantity of food
there are 300 calories in 100 g of a certain food
300 calories : 100 g food
how many calories are there in a 30 g portion of food
Let x = number of calories
x calories : 30 g food
Equate both ratios
300 calories : 100 g food = x calories : 30 g food
300/100 = x/30
300 * 30 = 100 * x
9000 = 100x
x = 9000/100
x = 90
x = number of calories = 90 calories
