X = 47 + 9y
xy = 1860

y(47 + 9y) = 1860
47y + 9y² = 1860
9y² + 47y - 1860 = 0

> using a quadratic equation solver on a calculator but you can also use the quadratic equation = [-b+/- √(b²-4ac)]/(2a)
> only integer solution is x = 12

12y = 1860
y = 155

integers are 12 and 155

8 0

3 years ago

From the yearbook receipts the students council deposited apart of the $1200 in a saving account receiving 9% interest per annum

Naddika [18.5K]

There was $800 deposited at 9% interest and $400 deposited at 4% interest.

The formula for simple interest is I = prt. Using our information we have:

88 = x(0.09)(1) + (1200-x)(0.04)(1)
88 = 0.09x + 48 - 0.04x
88 = 0.05x + 48

Subtract 48 from both sides:
88 - 48 = 0.05x + 48 - 48
40 = 0.05x

Divide both sides by 0.05:
40/0.05 = 0.05x/0.05
x = 800
1200 - x = 400

8 0

3 years ago