First you add them and then factor them the biggest factor is the answer
Answer:
7 times during the first 15 minutes
Step-by-step explanation:
Remember that

so

Decompose the numbers 18 and 42 in prime factors
we know that


Find the least common multiple (LCM)
The LCM is

we need to find all multiples of 126 that are less than or equal 900.

therefore
7 times during the first 15 minutes
1/2 ; you must look at rise over run. It goes up by one, runs over 2. 1/2 is a half
Surface are of a rectangular prism = 2(l x w + l x h + w x h) = 2(10 x 3 + 10x + 3x) = 2(30 + 13x) = 60 + 26x
Volume of a rectangular prism = l x w x h = 10 * 3 * x = 30x
Since surface area = volume
60 + 26x = 30x
4x = 60
x = 15 in
Since it’s asking for square inches on a rectangular prism, this is solving for surface area. So we use the following formula:
2(h*w)+2(h*l)+2(w*l)=A
2(10*8)+2(10*12)+2(8*12)
2(80)+2(120)+2(96)
160+240+192
592
592 sq. in.