a brother is 12 years older than his sister. four years ago, the brother was 3 times as old as the sister is now. how old is the broter now? a 12 b 14 c 16 d 18

C. 16

Step-by-step explanation:

Brother - b years now.

Sister - s years now.

A brother is 12 years older than his sister.

b - s = 12

(b - 4) - brother 4 years ago.

Four years ago, the brother was 3 times as old as the sister is now.

b - 4 = 3s

b - s = 12 > s = b - 12

b - 4 = 3s

b - 4 = 3(b - 12)

b - 4 = 3b - 36

36 - 4 = 3b - b

32 = 2b

b = 16

C. 16

Step-by-step explanation:

Let the brother's age be x.

Let the sister's age be y.

x = y + 12

x - 4 = 3y

Put x as y + 12 in the second equation.

y + 12 - 4 = 3y

y + 8 = 3y

8 = 3y - y

8 = 2y

y = 4

Put y as 4 in the first equation.

x = 4 + 12

x = 16

The brother is 16 years old and the sister is 4 years old.

positive

step-by-step explanation:

the quadrant is facing upwards

d. $180

step-by-step explanation:

if the dimensions of the room is 9ft by 12 ft, we have the area of the floor as,

so the area of the floor is 108 square feet, converting that into square yards we get,

the cost of carpet is $15 per square yard, therefore the cost of carpet for 12 square yards is,

hence, the cost of carpet is $180.

assuming the dimensions of the room be,

15 ft by 12 ft

so, the area of the floor of that room is,

we can convert 180 square feet into square yards, we know that,

1 sq ft = 0.111 sq yard

so, 180 square feet is,

so the area of floor is 20 square yards.

now, the cost of carpet is 15 dollars per square yard, therefore the cost of carpet for 20 square yards is,

so, it will cost $300.