I do believe it is 12 as well considering the fact that it's negative three and not positive. If it was a positive three then maybe it would be 18.
X = 1 hr lessons and y = 1/2 hr lessons
x + y = 35......y = 35 - x
40x + 25y = 1115
40x + 25(35 - x) = 1115
40x + 875 - 25x = 1115
40x - 25x = 1115 - 875
15x = 240
x = 240/15
x = 16 <=== there are 16 one-hr lessons
and 19 half-hr lessons
Tenths 43.5
hundredths 43.60
ones 44
Answer:
Girls = 16
Total students = 40
Step-by-step explanation:
40% of the students are girls, this means 60% of the students are boys.
To find the number of girls, setup a proportion using the percentages and actual number of students in the class. I am going to make the numerator the numbers that go with the girls and the denominator will be the numbers that go with the boys.
Also let's convert the percentages to decimals by moving the decimal two places left.
40% = 0.4 and 60% = 0.6

Now let's find the total number of students by adding the number of girls to the number of boys.
16 + 24 = 40