Benjamin bought tokens at a funfair. He used 3/8 of them at the ring-toss booth and 2/5 of the remaining tokens at the darts booth. He then bought another 35 to

a = amount of token at first

used at ring toss = 3/8 a

used at dart = 2/5 × (remaining from ring toss)
                     = 2/5 × (a - 3/8 a)
                     = 2/5 × 5/8 a
                     = 2/8 a


remaining from ring toss and dart + 35 = total tokens + 10
(total - used at ring - used at dart) + 35 = total tokens + 10
(a - 3/8 a - 2/8 a) + 35 = a + 10
3/8 a + 35 = a + 10
35 - 10 = a - 3/8 a
25 = 5/8 a
a = 25 × 8 ÷ 5
a = 40


So, total tokens at first is 40