a. using the same ratios:
26 : x = 8 : 12
x = (26*12)/8
x = 312/8
x = 39 $
b. using the same ratios:
5 : x = 20 : 10
x = (5*10)/20
x = 50/20
x = 2,5$
c. Sinea:
5 : 12 = 40 : x
x = (12*40)/5
x = 480/5
x = 96$
Ren:
10 : 20 = 40 : x
x = (40*20)/10
x = 800/10
x = 80$
Sinea would spend more money because the ratio of her money spend on souvenirs and snacks is 12/5 = 2,4 which is bigger than in Ben's case, where it's 20/10 = 2, hence SInea would spend more money.