If Marvin solved 40 math problems yesterday, he has solved 40*3 = <<40*3=120>>120 math problems today.
The total number of math problems that Marvin has practiced is 120+40 = <<120+40=160>>160
Arvin has practiced twice as many as Marvin, so has practiced 160 * 2 = <<160*2=320>>320 problems.
Together, Marvin and Arvin have solved 320+160 = <<320+160=480>>480 math problems.
#### 480