Althea has 100 trading cards and Marlon has 20. Every day Althea gives Marlon one card. Use the equations "c=100-d" and "c=20+d" to model this situation. Solve the system by substitution. Explain what the solution means in this situation.

Step-by-step explanation:

C is the Althea's and Marlon's letter

D is the amount of cards that Althea gives and Marlon receives..

answer: 42

use a calculator to find that 845/73 = 11.575

the whole part of the answer is 11. multiply this by 73 to get 11*73 = 803.

subtract that result from 845 to get 845 - 803 = 42

u = -(6/7)w

step-by-step explanation:

place all values with 'u' on one side of the equation.

4u + 8w = - 3u + 2w

4u + 3u = 2w - 8w

further simplify the equation by solving the addition and subtraction.

7u = - 6w

make 'u' the independent variable by placing its co-efficient on the right-hand side.

u = - (6/7)w