The answers is 14 if you follow the equation i just did it on a calculator (attached)
Slope = rise/run =[y2-y1]/[x2-x1]
1) slope = [90 - 30] / [12 - 4] = 60 / 8 = 15/2
2) slope = [75 - 30] / [10 - 4] = 45 / 6 = 15 / 2
The slopps are equal.
the difference between a full jug and a jug that is half full will give us the weight of the marbles only in a half full jug:
4 - 2.6 = 1.4 kg
In a half full jug that weighs 2.6 kg, the weight of the marbles is 1.4 kg
the weight of the jug = 2.6 - 1.4 = 1.2 kg