Grady gave 2/5 * 20 cubes = <<2/5*20=8>>8 of his red numbered cubes to Gage.
If Gage initially had 10 red numbered cubes, his total number of red numbered cubes became 10 cubes + 8 cubes = <<10+8=18>>18 cubes after Grady gave him 8 more.
Grady also gave 1/3 * 15 cubes = <<1/3*15=5>>5 blue numbered cubes to Gage.
This increased Gage's total number of blue numbered cubes to 12 cubes + 5 cubes = <<12+5=17>>17 cubes
The total number of cubes Gage has is now 17 cubes + 18 cubes = <<17+18=35>>35 cubes
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