There are 30 Year 6 students and 40 Year 7 students in a group. 10% of the Year 6 students and 25% of the Year 7 students are vegan. How many vegans are in the group altogether?
There are 30 x 10/100 = <<30*10/100=3>>3 Year 6 students who are vegan.
There are 40 x 25/100 = <<40*25/100=10>>10 Year 7 students who are vegan.
Therefore, there are a total of 3 + 10 = <<3+10=13>>13 vegan students in the group. Answer: \boxed{13}.