Something

addition:	addi $v0, $0, 4
		la $a0, str1
		syscall
		addi $v0, $0, 6
		syscall
		add.s $f1, $f1, $f0
		
		addi $v0, $0, 4
		la $a0, str2
		syscall
		addi $v0, $0, 12
		syscall
		beq $v0, $t3, addition
		beq $v0, $t4, subtract
		beq $v0, $t5, equals

substract:	addi $v0, $0, 4
		la $a0, str1
		syscall
		addi $v0, $0, 6
		syscall
		sub.s $f1, $f1, $f0
		
		addi $v0, $0, 4
		la $a0, str2
		syscall
		addi $v0, $0, 12
		syscall
		beq $v0, $t3, addition
		beq $v0, $t4, subtract
		beq $v0, $t5, equals

equals:		addi $v0, $0, 4
		la $a0, str3
		syscall
		addi $v0, $0, 2
		add.s $f12, $f31, $f1
		syscall

		jr $ra