Method chaining: class Number

Execute the statements $number = new Number(10); and $number->printInfo();

$x = 10

Execute the statement $number->add(90)->multiply(3)->printInfo();

$x = 300

Execute the statement $number->printInfo()->multiply(0.1)->printInfo()->add(5)->printInfo();

$x = 300

$x = 30

$x = 35