x = pounds of 75% protein supplement

1800 - x = pounds of 25% protein ration {there are 1800 pounds total}

0.75x + 0.25(1800 - x) = 0.7(1800) {pounds times percent equals total pounds in mixture}

0.75x + 450 - 0.25x = 1260 {used distributive property and multiplied}

0.5x + 450 = 1260 {combined like terms}

0.5x = 810 {subtracted 450 from each side}

x = 1620 {divided each side by 0.5}

1800 - x = 180 {substituted 1620, in for x, into 1800 - x}

**1620 pounds of 75% supplement
**

180 pounds of 25% ration*- Algebra House*
**
**