I'm assuming that the 3434 is a typo error. It should be 34.
Marni: 18 + 0.80m
Sharika: 12 + 0.9m
x = Sharika's minutes
x + 34 = Marni's minutes
[18 + 0.80(x+34)] + [12 + 0.90(x)] = 264
18 + 0.80x + 27.2 + 12 + 0.90x = 264
0.80x + 0.90x = 264 - 18 - 27.2 - 12
1.70x = 206.80
x = 206.80/1.70
x = 121.65 or 122
x + 34 = 122 + 34 = 156 minutes.
Hmm... I would say the equation would look like 3+5x=72/4.
3+5x=72/4
3+5x=18
5x=18-3
5x=15
x=15/5
x=3
The number is 3
7.5 is 30 percent of 25 because
25 divided by 10 is 2.5 times 3 is 7.5
I don't know the answer, but I suggest downloading the app: PhotoMath. It scans a math problem and shows you how to complete the problem. I hope this helped~!