Rates & principles

I would like to know if I am on the right track to writin this as a "systems of equations" using the substitution process. How much further do I have to go if this is right so far? A family made an investment for 1 year that earned $7.50 simple interest. If the principal had been $25 more and the interest rate 1% less, the interest would have been the same. Find the principal and the rate. 750/r = Pr/r, 7.50(P = 25)(p - .01), 7.50/775/r)(r - .01)

Linear Programing/Simplex Method

A company makes product 1 and product 2 from two resources. The linear programming model for determining the amounts of product 1 and 2 to product (X1 and X2) is: maximize Z = 8X1 + 2X2 (profit, $) subject to 4X1 + 5X2 < 20 (resource 1, lb) 2X1 + 6X2 < 18 (resource 2, lb) X1, X2 > 00 I need to solve this model using the simplex method.

Linear Programning

A baby products firm produces a strained baby food containing liver and milk, each of which contribute protein and iron to the baby food. Each jar of baby food must have 36 milligrams of protein and 50 milligrams of iron. The company has developed the following linear programming model to determine the number of ounces of liver (X1) and milk (X2) to include in each jar of baby food to meet the requirements for protein and iron at the minimum cost. mimimize Z = 0.05 X1 + 0.10 X2 (cost, $) subject to 6X1 + 2X2 > 36 (protein, mg) 5X1 + 5X2 > 50 (iron, mg,) X1, X2 > 00 I must complete this model using the simplex method

Linear Programing/Simplex Method

A jewelry store makes both necklaces and bracelets from gold and platinum. The store has developed the following linear programming model for determining the number of necklaces and bracelets (X1 and X2) that it needs to make to maximize profit. maximize Z = 300X1 + 400X2 (profit, $) subject to 3X1 + 2X2 < 18 (gold, oz) 2X1 + 4X2 < 20 (platinum, oz) X2 < 04 (demand, bracelets) X1, X2 > 0 I need to solve this problem using the simplex method.

Matricies to solve equation

please help