if you put it in algebraic terms, and pizza is p, soda is s
1p + 1s = 1.99
3p + 2s = 5.48
to find the cost individually you use simultaneous equations
by multiplying the top equation by 2 you get
2p + 2s = 3.98
and then you can say that 1p is 5.48-3.98 = 1.50
and if 1p = 1.50, 1s = 1.99-1.50=49