1.
	15:42 + 16:40 + 17:23 + 15:29 = 01:05:14
2.
	a ≈ -3
	b ≈  3

	-3:3 = -1

	-3+3 = 0
3.

	4     1       3
	–  -  –  =  –  = 0,75
	4     4       4
                                        2
	0,75:3 = 0,25*2 =  –
                                        3

	2
	–  = 0,50
	3
                                   3
	0,50 + 0,25 = 0,75 =  –
			      4

5.
	54zap     135zap                            4,2*135
	-------  = ------                    X = -------------------- = 10,5g
	 4,2g         X                                      54



	54zap        X                                   54*1,4
	-------  = ------                     X = ---------------- = 18
           4,2g       1,4g                                    4,2
6.
	I. (33)4  = 312
         II. 33 * 34 = 37
         III. 36 : 32 = 34
	IV. (36)2 = 312


8.
	 28         X                                    75*28
	----- = ------                       X = ---------------- = 105
	20%     75%                                   20