lavre has sixty-one coins, all of whichare dimes and quaters. if the total value of the coins is $9.85, how many of each kind of coins has she?
grade 9 math!!!!!!!!!! please help - DrBob222, Sunday, March 8, 2009 at 10:49pm
If Q = # quarters
and D = # dimes.
Two equations and two unknowns. Solve for Q and D. Check my work.
grade 9 math!!!!!!!!!! please help - Anonymous, Monday, March 9, 2009 at 1:33pm
Q = 25
D = 36
It's a system of linear equations so you can put it into a matrix to solve
let Matrix A be a 2x2 matrix
and have another matrix, B
A^-1 * B will give you the answer