let

t = the cost of a toy

p = the cost of a pen

3 similar toys and 5 similar pens cost $83.20

3t + 5p = 83.20

5 toys and 3 such pens cost $88

5t + 3p = 88

by solving the system of equations

3t + 5p = 83.20

5t + 3p = 88

we find

t = $11.9

p = $9.5

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7p + 4t = 7*9.5 + 4*11.9 = $114.1

the total cost of 7 pens and 4 toys is $114.1.