Answer:
99 marbles
Explanation:
Let number of marbles with Alex be

Leanne has 1/2 as many marbles as Alex.
So,
Number of marbles with Leanne =

Number of marbles with Joachim =

Also, Alex has 36 more marbles than Joachim.
So,
Number of marbles with Alex = 36 + Number of marbles with Joachim
=

So,

So,
Number of marbles with Alex = 54
Number of marbles with Leanne =

Number of marbles with Joachim =

Total number of marbles =
