Q10: Subtract the area of the smaller unshaded triangle from the bigger triangle to find the shaded area.

For the second question, you dont know how many exact units Paul has in relation to the total number of units (i.e. You only know paul has 3Units-6 coins), so instead of drawing a model, it might be easier if you take the total number of coins paul and jimmy has together and equate it to the total number of units, then find the value of one unit before you work out the number of coins paul has.