Mrs. yuri’s classroom has 21 students. she took all of her students to a field trip at the skate station and brought four chaperones. the students, chaperones and mrs. yurirented either regular skates for $4.25 or inline skates for $7.50 per day. mrs. yuri paid a total of $143.00 for skates’ rental.

Setup a system of equations.

r + I = 26
4.25r + 7.50i = 143.00
r = 26-i
Plug r = 26-i into 2nd equation and solve

4.25(26-i) + 7.50i = 143.00
110.50 - 4.25i + 7.50i = 143.00
110.50 + 3.25i = 143.00
Subtract 110.50 from both sides
3.25i = 32.50
Divide both sides by 3.25
I = 10
10 pairs of inline skates
26-10= 16
16 pairs of regular skates