Этот мужчина пытается продать картину и говорить что она была написана художником в 1800 года не знаешь что это неправда почему

This man is trying to sell a picture and saying that it was painted by the artist in the year 1800 did not know that it is not true Why

he knows mathematics much better than he did last year.he must   work a lot in summer.2.your mathematics is very poor.you must to work at it in summer.3.where is peter? -oh,he must read in the library.he is getting ready for a very difficult examination.4.you must to study english for several years already.your language is very good.5.oh,look how white and clean everything is! it must to snow at night.6.oh,you are all in snow,you look like a snowman.it must   snow heavily.7.look,what huge snowdrefts yhere are everywhere,and the path is covered with knee-deep snow.it must to snow for several hours already.8.you look fresh! you must   have a good sleep at night.9.9you look very tired.you must have a good sleep at night

2* 3 * 4   -   (20 : 5 + 3) + 152 = 169                            1) 20 : 5 + 3 = 4 + 3 = 7                              2) 2 * 3 * 4 = 6 * 4 = 24                              3) 24 -  7 + 152 = 17 + 152 = 169607   -     6 * 6 : (13 - 4)     +   48 : 8   = 609                              1) 6 * 6 : ( 13 - 4) = 6 * 6 : 9 = 36 : 9 = 4                              2) 48 : 8 = 6                              3) 607 - 4 + 6 = 60954 : ( 21 - 15 ) * 8     -     63 : 7    -   ( 134 - 128 ) =   57              1) 54 : ( 21 - 15 ) * 8 = 54 : 6 * 8 = 9 * 8 = 72                            2) 134 - 128 = 6                            3) 63 : 7 = 9                            4) 72 - 9 - 6 = 57( первым действием всегда считаем то, что в   именно в этом порядке я и делала)