... + 12 cm = 60 cm.9. 4Substitute 2 for xand 5 for y:(3xy+ x)ᎏxyᎏ=((3) (2) (5) + 2) ᎏ 2 5ᎏ= (30 + 2) ᎏ 2 5ᎏ= 32 ᎏ 2 5ᎏ= (͙5 32 ෆ) 2 = 2 2= 4. Or, 3 (2) (5) = 30, 30 + 2 = 32, ... equationto find the value of a:–6b + 2a – 25 = 5,–6(–3) + 2a – 25 = 5, 18 + 2a = 30, 2a = 12, a = 6. Finally, (ᎏabᎏ) 2 = (ᎏ–63ᎏ) 2 = (–ᎏ1 2 ᎏ) 2 = ᎏ14ᎏ.13. 6 If j@k = –8 when ... equal to 2 r 2 , or 2 (9) 2 = 2( 81)π = 1 62 square units.8. d. Cross multiply:a 20 ෆ= a 2 20 ෆ= 2 180ෆa 2 ͙4ෆ͙5ෆ= 2 36ෆ͙5ෆ2a 2 ͙5ෆ= 12 5ෆa 2 = 6a = ͙6ෆ9. b. Since triangle DEC...