Question

400 trees 35% mango trees 42% apple trees in there how many grapes vine there

Answer 1

mango- 35/100*400=140
apple- 42/100*400=168
grape- 400-140-168=92

grape vines are 92

Answer 2

No of mango trees = 35 /100  x 400 = 140 
No of apple trees = 42/100 x 400 = 168 

Mango + Apple trees = 140 +168  = 308 

So, the remaining i.e 400 - 308 = 92 trees might be the grape trees according to your question. 

Percentage of grape trees :

92 = 4 x ⇔ x = 23%