We have three types of a sand/salt/ash mix. The first type is25% sand, 10% salt, and 65% ash. The second type is 30% sand, 40% salt, and 30% ash. The third type is 70%

sand, 15% salt, and 15% ash. We need a mixture that will be 40% s and, 25% salt, and 35% ash. Find how much of each type should be combined to obtain this mixture.

Make sure to write down the system of equations that represents this problem and the translation of that system into a matrix.