Algebra

Let x be the cost for one pound of almond and y be the cost for one pound of jelly bean

Making a system of equations:

$3x + 5y = 24$

$9x+7y = 42$

Multiplying the first equation by -3 and we get

$-9x- 15y = -72$

$9x +7y = 42$

Then we add both equations together

$y = \frac{30}{8} = \boxed{3.75}$

Then we plug 3.75 in for y in the first equation

$3x + 5(3.75) = 24$

$3x + 18.75 = 24$

$3x = 5.25$

$x = \boxed{1.75}$

So one pound of almond cost $$1.75$ and one pound of jelly bean cost $$3.75$.