7. The cost of 4 boxes of pens and 3 boxes of penclls is $22.55. The cost of 3 boxes of pens and 2 boxes of penclls is $16.45. Find the cost of each.

1. 2. ∠b and ∠y are right angles. 3.? 4.? which two statements are missing in steps 3 and 4? ∠x ≅ ∠c △abc ~ △zyx by the sas similarity theorem. ∠b ≅ ∠y △abc ~ △zyx by the sas similarity theorem. = 2 △abc ~ △zyx by the sss similarity theorem. = 2 △abc ~ △zyx by the sss similarity theorem.